1. Field of the Invention
The present invention relates to information handling systems and more particularly to electro magnetic interference (EMI) shielding of information handling systems.
2. Description of the Related Art
As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
One important aspect in the design of information handling systems is the shielding of electromagnetic energy. In the design of most information handling systems, it is desirable to shield the system from unwanted electromagnetic interference from external sources, as well as to contain electromagnetic energy generated by the system itself. Furthermore, certain government regulations (e.g., Federal Communications Commission requirements) may necessitate that electronic systems be designed to contain electromagnetic noise within certain specifications.
Often with information handling systems, grounding is desirable between a peripheral card and its slot in the chassis to provide sufficient EMI containment. There are several known issues relating to providing this grounding. For example, it is desirable to provide a chassis structure which rather then including die cast rear wall uses sheet metal structure, which would inherently reduce the stiffness of the chassis. Also for example, often it is determined late in a design process that a particular EMI suppression feature is no longer needed. In this case, the decision to remove an EMI feature generally results in undesirable changes to hard tooling. Also for example, known solutions are often prone to being damaged during handling and normal use.
Known methods of peripheral card EMI suppression generally relate to one of two types of designs. A first design uses a thin metal plate attached to the chassis which contains spring arms or clips that contact the card mounting bracket. Another design uses a fabric over foam gasket adhered to the chassis which contacts the card mounting bracket. Each of these methods has inherent issues. For example, the fabric over foam gaskets can easily be sheared off, peeled off, or deformed, and also reduce possible venting areas. Alternately, the thin metal plates are often very flimsy and easy to snag, rip, and deform.
Accordingly, it is desirable to provide an EMI shielding scheme which addresses and improves upon all three of these issues. It is also desirable to provide an EMI shielding scheme which reduces costs associated with this portion of the chassis.